Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2017

Stock-Based Compensation

Summary of stock option activity under the Equity Plans

	Options			Weighted Average Exercise Price Per Share		Weighted Average Remaining Life in Years		Aggregate Intrinsic Value
Outstanding at December 31, 2015		59,274		$	4.95		7.90
Forfeited		(6,046	)	$	5.14
Outstanding at December 31, 2016		53,228		$	4.93		7.00	$	213
Granted		2,220,858		$	12.51
Exercised		(3,506	)	$	5.55
Forfeited		(12,959	)	$	5.78
Outstanding at December 31, 2017		2,257,621		$	12.38		8.66	$	68
Options exercisable at December 31, 2017		716,316		$	19.62		7.35	$	65
Options vested and expected to vest at December 31, 2017		2,257,621		$	12.38		8.66	$	68

Schedule of assumptions used to determine grant-date fair value of stock options

	Year Ended December 31,
	2017
Expected volatility		68.7	%
Weighted average risk-free interest rate		2.1	%
Expected dividend yield		0.0	%
Expected term (in years)		6.6

Schedule of stock-based compensation expense classified in the consolidated statements of operations

	Year Ended December 31,
	2017		2016
Research and development	$	1,834	$	35
General and administrative		3,766		10
Total	$	5,600	$	45